Measure the exterior envelope by elevation
Measure each wall width by its height and keep the four elevations separate. For a simple 40-by-30-foot footprint with 9-foot rectangular walls, the perimeter is 140 feet and the base wall area is 1,260 square feet before gables and openings. This is a geometry example only; actual wall heights, additions, and cladding details must be measured.
Add triangular gables as one-half base times height. Measure dormer faces, exposed foundation trim, fascia, and other included elements separately. Deduct only substantial windows and doors; detailed trim and extra cutting can offset small opening deductions. The house stain calculator provides a starting total that should be checked against elevation notes.
One coat or two is a product decision
Do not use “new wood equals two coats” as a universal rule. Penetrating stains, wet-on-wet systems, and film-forming solid stains can have very different application requirements. Read the technical instructions for the exact product, substrate, and desired opacity. The specified spread rate may also differ between the first and later coats.
A maintenance coat is appropriate only when the existing finish is compatible, well bonded, clean, and within the product system’s recoat guidance. Peeling, heavy build-up, widespread greying, or an unknown previous coating calls for closer diagnosis and possibly stripping or a different preparation system.
- One application: use only where the product specifies it
- Wet-on-wet passes: complete within the maker’s timing window
- Separate coats: observe the stated drying and recoat interval
- Maintenance coat: verify adhesion and compatibility first
Estimate each coat with the correct rate
Divide measured area by the label coverage for the first coat. If a second coat is required and has a different spread rate, calculate it separately rather than simply doubling the first-coat quantity. Rough cedar, logs, end grain, and deeply weathered wood may use more material than smooth siding, so select the label range that matches the prepared surface.
Spray application can lose material to wind and overspray; back-brushing may be required for penetration and evenness. Use the product maker’s stated allowance and local test-area use instead of a universal waste percentage. Keep separate calculations when siding, trim, deck surfaces, or logs use different products.
Prepare for adhesion and uniform colour
Inspect for moisture entry, rot, failed caulking, loose fasteners, biological growth, and peeling finish. Correct the cause of deterioration before cosmetic work. Clean using a method compatible with the substrate, rinse residues, and let the assembly dry to the condition required by the stain maker. Sand or strip as directed, taking suitable precautions for old or unknown coatings.
Box compatible containers together when the manufacturer recommends it, and work to natural breaks such as corners or boards. Maintain a wet edge to reduce lap marks. Apply a test area where it can be evaluated after full drying; colour and opacity on rough wood often differ from a small store sample.
Wait for the complete weather window
Check the forecast against the label’s limits for air and surface temperature, direct sun, wind, humidity, rain, and overnight dew. The wall surface can be much hotter in sun or cooler in shade than the reported air temperature. In Canadian spring and autumn conditions, a suitable afternoon can still be followed by a night below the product’s curing range.
Plan staging so each elevation can be completed to a natural break. Follow appropriate ladder, scaffold, and fall-protection practices for the site; material estimation does not make high work safe. Protect roofs, masonry, glazing, plants, vehicles, and neighbouring property from cleaner and overspray.
Inspect and maintain by exposure
Recoat when inspection and manufacturer guidance indicate it, before widespread failure makes preparation more invasive. Horizontal rail caps and trim can age faster than vertical siding and may need separate attention. Use the fence or deck stain calculator for those surfaces rather than folding them into the house-wall rate.
- Check south- and west-facing walls for faster weathering
- Inspect lower courses, end grain, and splash zones after wet seasons
- Clean gently without damaging the stain film or wood fibres
- Record product, colour, batch, prep, coat count, and application date